Oil composition for minimal quantity lubrication aluminum processing

ABSTRACT

The present invention provides an oil for minimal quantity lubrication aluminum processing. In aluminum processing such as cutting, grinding, and form-rolling, the oil composition can improve the processing efficiency, tool life, and handleability in higher levels in a well-balanced manner and further is highly biodegradable and thus environment friendly. The oil composition comprises an alcohol compound having 1 to 8 hydroxyl groups and 2 to 27 carbon atoms, in an amount of 16 to 100 percent by mass on the basis of the total mass of the composition.

The present invention relates to oil compositions for minimal quantitylubrication aluminum processing.

Examples of aluminum processing include cutting, grinding, form-rolling,forging, pressing, drawing, and rolling. These aluminum processingoperations are usually carried out using lubricating oils.

For example, in cutting and grinding operations, cutting and grindingoils have been used in order to extend the working life of tools such asdrills, end mills, tool bits, grinding stones and the like, improve theroughness of the finished surface of a workpiece, and improve theprocessing efficiency thereby, resulting in an improvement in theproductivity of machining.

Cutting or grinding oils are roughly classified into two main types ofoils, i.e., water-soluble oils which are put in use after diluting thesurface-active agent and lubricant component contained therein withwater, and water-insoluble oils which contain a mineral oil as a maincomponent and are used as it is, i.e., in the form of a stock solution.In the conventional cutting and grinding operations, a relatively largeamount of a cutting and grinding oil is supplied to processing spots ofa workpiece regardless of which type of oil is used.

The most basic and important functions of cutting and grinding oils arelubricating and cooling functions. In general, water-insoluble cuttingand grinding oils are superior in lubricating properties, whilewater-soluble ones are superior in cooling properties. It is thusnecessary to supply the water-insoluble cutting and grinding oil inlarge amounts, ranging from several liters to over ten liters perminute.

Cutting and grinding oils, which are effective in improving processingefficiency have undesirable aspects, from different viewpoints. Atypical example of such aspects is environmental impacts. Regardless ofwhether water-soluble or water-insoluble, the oils tends to graduallydeteriorate during the use thereof and finally become incapable offurther use. For instance, a water-soluble oil becomes unable to be usedwhen it undergoes the separation of the components or deteriorates theenvironmental sanitation, caused by deteriorated stability due to thegrowth of microorganisms. A water-insoluble oil becomes unusable whenthe acidic components generated with the progress of oxidation make aworkpiece corrode, or the viscosity is significantly changed.Furthermore, the oil is spent by adhering to metal chips or machiningswarf and becomes wastes.

In such a case, the deteriorated oil is disposed and then replaced witha fresh oil. The oil disposed as wastes is necessarily subjected tovarious treatments so as to avoid the waste oil from adversely affectingthe environment. For instance, cutting or grinding oils that aredeveloped for the primary purpose of improving processing efficiency,contain a large amount of chlorine-containing components which maygenerate harmful dioxin during thermal disposal. Removal of suchcomponents is thus required. As the result, cutting or grinding oilsthat are free of chlorine-containing components have been developed.However, even though the oils contain no chlorine-containing component,they would adversely affect the environment if their waste disposalvolume is large. The water-soluble oils may pollute the surroundingwater area, and are, therefore, necessarily subjected tohighly-developed treatments that require large costs.

The use of cooling by cold air blowing instead of the use of cutting andgrinding oils has just been studied in order to deal with the problemsas described above. However, in this case, the other functions ofcutting and grinding oils, i.e., lubricity can not be obtained.

Under these circumstances, a minimal quantity lubrication cutting andgrinding processing system has been developed, which is carried out bysupplying oil in a trace amount of 1/100000 to 1/1000000 of the amountof oil used for conventional cutting and grinding to processing spots,together with a compressed fluid (for example, compressed air). Thissystem can obtain a cooling effect with compressed air and can reducethe amount of wastes due to the use of a minimal quantity of oil,resulting in an improvement in effects on the environment that is causedby large amounts of waste disposal (see, for example, patent literature1 below).

In such a minimal quantity lubrication cutting and grinding processingmethod, additives such as oiliness improvers and extreme pressureadditives were conventionally used to improve the processing efficiency.In particular, oiliness improvers such as alcohols, carboxylic acids,sulfides of unsaturated carboxylic acids, polyoxyalkylene compounds,esters, hydrocarbyl ethers of polyhydric alcohols, and amines are usedand added in an amount of usually 0.1 to 15 percent by mass on the basisof the total mass of a composition (see, for example, patent literature2 below).

CITATION LIST

-   Patent Literature-   Patent Literature 1: WO02/081605-   Patent Literature 2: Japanese Patent Laid-Open Publication No.    2006-249369

SUMMARY OF INVENTION Technical Problem

Recently, the above-mentioned lubricating oil used for aluminumprocessing have been required to be further improved in properties. Forexample, in cutting and grinding processing utilizing the minimalquantity lubrication system (MQL system), it is required to provide aworkpiece with excellent finished surfaces even though the amount of oilto be supplied is minimal, to reduce the wear of tools, and to carry outcutting and grinding efficiently. Therefore, the cutting and grindingoil used for the system is required to have high quality properties. Sofar, an ester has been used to reduce the friction and wear possiblyoccurring during processing such as aluminum cutting. The ester has beenused not only as an additive but also as a base oil composing themajority of an oil because of its high lubricity and stability.

However, an oil containing mainly an ester has a certain limit in itsproperties. A processing oil that is more highly efficient has beensought in order to further enhance productivity, and it has thus becomean urgent matter to develop such a processing oil.

Solution to Problem

The present invention was accomplished in view of these circumstancesand has an object to provide an aluminum processing oil compositionsuitable for MQL system and achievable of enhanced processingproperties.

As the results of extensive studies and research carried out to achievethe foregoing object, the present invention was accomplished on thebasis of the finding that the object was able to be achieved using anoil composition comprising an alcohol compound with a specific structurein a specific amount.

That is, the present invention relates to an oil composition for minimalquantity lubrication aluminum processing, comprising an alcohol compoundhaving 1 to 8 hydroxyl groups and 2 to 27 carbon atoms, in an amount of16 to 100 percent by mass on the basis of the total mass of thecomposition.

Advantageous Effects of Invention

In cutting, grinding and form-rolling aluminum processing, the oilcomposition for minimal quantity lubrication aluminum processing canimprove the processing efficiency, tool life and handleabilitysufficiently in a well-balance manner.

DESCRIPTION OF EMBODIMENTS

The present invention will be described below.

The oil composition for aluminum processing by minimal quantitylubrication system is an alcohol compound having 1 to 8 hydroxyl groupsand 2 to 27 carbon atoms (hereinafter, referred to as “the alcoholcompound of the present invention”). The use of the alcohol compound ofthe present invention as the oil composition can improve the processingefficiency, tool life and handleability in higher levels and in awell-balance manner.

The alcohol compound may be an monohydric alcohol, and is preferably astraight-chain or branched alcohol having 3 to 18 carbon atoms or acycloalkyl alcohol or alkylcylcoalkyl alcohol, having 5 to 10 carbonatoms. Specific examples include straight-chain or branched propanol(n-propanol, 1-methylethanol), straight-chain or branched butanol(n-butanol, 1-methylpropanol, 2-methylpropanol), straight-chain orbranched pentanol (n-pentanol, 1-methylbutanol, 2-methylbutanol,3-methylbutanol), straight-chain or branched hexanol (n-hexanol,1-methylpentanol, 2-methylpentanol, 3-methylpentanol), straight-chain orbranched heptanol (n-heptanol, 1-methylhexanol, 2-methylhexanol,3-methylhexanol, 4-methylhexanol, 5-methylhexanol,2,4-dimethylpentanol), straight-chain or branched octanol (n-octanol,2-ethylhexanol, 1-methylheptanol, 2-methylheptanol), straight-chain orbranched nonanol (n-nonanol, 1-methylocatanol, 3,5,5-trimethylhexanol,1-(2′-methylpropyl)-3-methylbutanol), straight-chain or branched decanol(n-decanol, iso-decanol), straight-chain or branched undecanol(n-undecanol), straight-chain or branched dodecanol (n-dodecanol,iso-dodecanol), straight-chain or branched tridecanol, straight-chain orbranched tetradecanol (n-tetradecanol, iso-tetradecanol), straight-chainor branched pentadecanol, straight-chain or branched hexadecanol(n-hexadecanol, iso-hexadecanol), straight-chain or branchedheptadecanol, straight-chain or branched octadecanol (n-octadecanol,iso-octadecanol), cyclopentanol, cyclohexanol, methylcyclohexanol,dimethylcyclohexanol, and cycloheptanol.

Alternatively, the alcohol compound of the present invention may be apolyhydric alcohol having 2 to 8 hydroxyl groups.

Specific examples of the dihydric alcohol (diols) include ethyleneglycol, 1,2-propane diol (propylene glycol), 1,3-propane diol,1,4-butane diol, 1,2-butane diol, 2-methyl-1,2-propane diol,2-methyl-1,3-propane diol, 1,3-butane diol, 1,4-butane diol, 1,2-pentanediol, 1,3-pentane diol, 1,4-pentane diol, 1,5-pentane diol, neopentylglycol, 1,6-hexane diol, 2-ethyl-2-methyl-1,3-propane diol, 1,7-heptanediol, 2-methyl-2-propyl-1,3-propane diol, 2,2-diethyl-1,3-propane diol,1,8-octane diol, 1,9-nonane diol, 1,10-decane diol, 1,11-undecane diol,and 1,12-dodecane diol.

Specific examples of the alcohols of trihydric or more includepolyhydric alcohols such as trimethylolethane, trimethylolpropane,trimethylolbutane, di-(trimethylolpropane), tri-(trimethylolpropane),pentaerythritol, di-(pentaerythritol), tri-(pentaerythritol), glycerin,polyglycerin (dimer to eicosamer thereof), 1,3,5-pentanetriol, sorbitol,sorbitan, sorbitol-glycerin condensate, adonitol, arabitol, xylitol, andmannitol; saccharide such as xylose, arabinose, ribose, rhamnose,glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose,isomaltose, trehalose, sucrose, raffinose, gentianose, and melezitose;and partial-etherified products and methylglucoside (glycosides)thereof. Preferred examples include hindered alcohols such as neopentylglycol, trimethylolethane, trimethylolpropane, trimethylolbutane,di-(trimethylolpropane), tri-(trimethylolpropane), pentaerythritol,di-(pentaerythritol), and tri-(pentaerythritol).

When any of the above-mentioned polyhydric alcohols is used, it may be apartial ester in which some of the hydroxyl groups are esterified.

Particularly preferred examples of the alcohol compound of the presentinvention include branched saturated monohydric alcohols in view ofprocessability of aluminum.

The alcohol compound of the present invention may be a mixture of two ormore of the above-described alcohols.

The content of the alcohol compound of the present invention isnecessarily 16 percent by mass or more, preferably 18 percent by mass ormore, more preferably 20 percent by mass or more on the basis of thetotal mass of the composition with the objective of improving processingefficiency and too life. The content is 100 percent by mass or less,preferably 95 percent by mass or less, more preferably 90 percent bymass or less, most preferably 80 percent by mass or less on the basis ofthe total mass of the composition in view of handleability.

The base oil of the aluminum processing oil composition of the presentinvention may be composed of the alcohol compound of the presentinvention alone or alternatively may be a mixture thereof with a baseoil that is used for an ordinary lubricant to an extent that theprocessing efficiency, tool life and treatability are not impaired. Sucha base oil may be a mineral oil or a synthetic oil. These oils may bemixed.

Examples of the mineral oils include paraffinic or naphthenic mineraloils produced by subjecting a lubricating oil fraction resulting fromatmospheric and vacuum distillation of crude oil, to any one or morerefining treatments selected from solvent deasphalting, solventextraction, hydrocracking, solvent dewaxing, catalytic dewaxing,hydrorefining, sulfuric acid treatment, and clay treatment.

Examples of the synthetic oil include poly-α-olefins such as propyleneoligomer, polybutene, polyisobutylene, 1-octene oligomer, 1-deceneoligomer, cooligomers of ethylene and propylene, cooligomers of ethyleneand 1-octene, and cooligomers of ethylene and 1-decene, and hydrogenatedcompounds of these compounds; isoparaffin; alkylbenzenes such asmonoalkylbenzenes, dialkylbenzenes and polyalkylbenzenes;alkylnaphthalenes such as monoalkylnaphthalenes, dialkylnaphthalenes andpolyalkylnaphthalenes; dibasic acid esters such as dioctyl adipate,di-2-ethylhexyl adipate, disodecyl adipate, ditridecyl adipate,di-2-ethylhexyl sebacate, and ditridecyl glutarate; tribasic acid esterssuch as trimellitic acid; polyolesters such as trimethylolpropanecaprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, and pentaerythritol pelargonate; polyglycols such aspolyethylene glycol, polypropylene glycol, polyoxyethyleneoxypropyleneglycol, polyethyleneglycol monoether, polypropylene glycol monoether,polyoxyethyleneoxypropylene glycol monoether, polyethylene glycoldiether, polypropylene glycol diether, and polyoxyethyleneoxypropyleneglycol diether; phenyl ethers such as monoalkyldiphenyl ether,dialkyldiphenyl ether, monoalkyltriphenyl ether, dialkyltriphenyl ether,tetraphenyl ether, monoalkyltetraphenyl ether, dialkyltetraphenyl ether,and pentaphenyl ether; silicone oil; and fluoroethers such asperfluoroether. These may be used alone or in combination.

Among the above-mentioned base oils, preferred are monoesters and/ordiesters (excluding alicyclic dicarboxylic acid ester compounds), morepreferred are the following (a) to (c) esters, and more preferred are(a) and (b) with the objective of further improving the handleability ofthe oil composition:

-   -   (a) an ester of a monohydric alcohol and a monobasic acid ester;    -   (b) an ester of a dihydric alcohol and a monobasic acid ester;    -   (c) an ester of a monohydric alcohol and a dibasic acid ester.

Examples of the monohydric alcohol and dihydric alcohol are the same asthe monohydric alcohols and dihydric alcohols exemplified with respectto the alcohol compounds of the present invention.

The monobasic acid is usually a fatty acid having 2 to 24 carbon atoms,which may be straight-chain or branched and saturated or unsaturated.Specific examples include fatty acids such as acetic acid, propionicacid, straight-chain or branched butanoic acid, straight-chain orbranched pentanoic acid, straight-chain or branched hexanoic acid,straight-chain or branched heptanoic acid, straight-chain or branchedoctanonic acid, straight-chain or branched nonanoic acid, straight-chainor branched decanoic acid, straight-chain or branched undecanoic acid,straight-chain or branched dodecanoic acid, straight-chain or branchedtridecanoic acid, straight-chain or branched tetradecanoic acid,straight-chain or branched pentadecanoic acid, straight-chain orbranched hexadecanoic acid, straight-chain or branched heptadecanoicacid, straight-chain or branched octadecanoic acid, straight-chain orbranched nonadecanoic acid, straight-chain or branched eicosanoic acid,straight-chain or branched heneicosanoic acid, straight-chain orbranched docosanoic acid, straight-chain or branched tricosanoic acid,and straight-chain or branched tetracosanoic acid; unsaturated fattyacids such as acrylic acid, straight-chain or branched butenoic acid,straight-chain or branched pentenoic acid, straight-chain or branchedhexenoic acid, straight-chain or branched heptenoic acid, straight-chainor branched octenoic acid, straight-chain or branched nonenoic acid,straight-chain or branched decenoic acid, straight-chain or branchedundecenoic acid, straight-chain or branched dodecenoic acid,straight-chain or branched tridecenoic acid, straight-chain or branchedtetradecenoic acid, straight-chain or branched pentadecenoic acid,straight-chain or branched hexadecenoic acid, straight-chain or branchedheptadecenoic acid, straight-chain or branched octadecenoic acid,straight-chain or branched nonadecenoic acid, straight-chain or branchedeicosenic acid, straight-chain or branched heneicosenic acid,straight-chain or branched docosenic acid, straight-chain or branchedtircosenic acid, and straight-chain or branched tetracosenic acid; andmixtures thereof. Among these, in view of processing efficiency, toollife, and handleability, preferred are saturated fatty acids having 3 to20 carbon atoms, unsaturated fatty acids having 3 to 22 carbon atoms,and mixtures thereof. More preferred are saturated fatty acids having 4to 18 carbon atoms, unsaturated fatty acids having 4 to 18 carbon atoms,and mixtures thereof. In view of anti-sticking properties, mostpreferred are saturated fatty acids having 4 to 18 carbon atoms.

The dibasic acid may be a dibasic acid having 2 to 16 carbon atoms,which may be straight-chain or branched and saturated or unsaturated.Specific examples include ethanedioic acid, propanedioic acid,straight-chain or branched butanedioic acid, straight-chain or branchedpentanedioic acid, straight-chain or branched hexanedioic acid,straight-chain or branched heptanedioic acid, straight-chain or branchedoctanedioic acid, straight-chain or branched nonanedioic acid,straight-chain or branched decanedioic acid, straight-chain or branchedundecanedioic acid, straight-chain or branched dodecandioic acid,straight-chain or branched tridecanedioic acid, straight-chain orbranched tetradecanedioic acid, straight-chain or branchedheptadecanedioic acid, and straight-chain or branched hexadecanedioicacid, straight-chain or branched hexenedioic acid, straight-chain orbranched heptenedioic acid, straight-chain or branched octenedioic acid,straight-chain or branched nonenedioic acid, straight-chain or brancheddecenedioic acid, straight-chain or branched undecenedioic acid,straight-chain or branched dodecenedioic acid, straight-chain orbranched tridecenedioic acid, straight-chain or branchedtetradecenedioic acid, straight-chain or branched heptadecenedioic acid,straight-chain or branched hexadecenedioic acid, and mixtures thereof.

The base oil of the oil composition for aluminum processing may be thealcohol compound of the present invention, the content of which may be16 percent by mass or more on the basis of the total mass of thecomposition. The contents and type of base oils other than the alcoholcompound of the present invention are not limited as long as theproperties of the composition are not impaired.

With the objective of improving processing efficiency and tool life, theoil composition for aluminum processing contains preferably an oilinessimprover. Examples of such an oiliness improver include (A) carboxylicacids, (B) sulfides of unsaturated carboxylic acids, (C) compoundsrepresented by formula (1) below, (D) compounds represented by formula(2) below, (E) polyoxyalkylene compounds, (F) esters, (G) hydrocarbylethers of polyhydric alcohols, and (H) amines.

[In formula (1), R¹ is a hydrocarbon group having 1 to 30 carbon atoms,a is an integer of 1 to 6, and b is an integer of 0 to 5.]

[In formula (2), R² is a hydrocarbon group having 1 to 30 carbon atoms,c is an integer of 1 to 6, and d is an integer of 0 to 5.]

Component (A), i.e., carboxylic acids may be monobasic or polybasicacids. With the objective of improving processing efficiency and toollife, preferred are monocarboxylic acids having 1 to 40 carbon atoms,more preferred are carboxylic acids having 5 to 25 carbon atoms, andmost preferred are carboxylic acids having 5 to 20 carbon atoms. Thesecarboxylic acids may be straight-chain or branched and saturated orunsaturated. However, in view of anti-sticking properties, thecarboxylic acids are preferably saturated carboxylic acids. Specificexamples include the monobasic acids and polybasic acid that are thesame as those exemplified with respect to the above-described ester.

Examples of (B) sulfides of unsaturated carboxylic acids includesulfides of unsaturated carboxylic acids selected from the abovedescribed (A) carboxylic acids. Preferred examples include sulfides ofoleic acid.

In (C) compounds represented by formula (1) above, examples of thehydrocarbon group having 1 to 30 carbon atoms represented by R¹ includestraight-chain or branched alkyl groups having 1 to 30 carbon atoms,cycloalkyl groups having 5 to 7 carbon atoms, alkylcycloalkyl groupshaving 6 to 30 carbon atoms, straight-chain or branched alkenyl groupshaving 2 to 30 carbon atoms, aryl groups having 6 to 10 carbon atoms,alkylaryl groups having 7 to 30 carbon atoms, and arylalkyl groupshaving 7 to 30 carbon atoms. Among these hydrocarbons, preferred arestraight-chain or branched alkyl groups having 1 to 30 carbon atoms,more preferred are straight-chain or branched alkyl groups having 1 to20 carbon atoms, more preferred are straight-chain or branched alkylgroups having 1 to 10 carbon atoms, and most preferred arestraight-chain or branched alkyl groups having 1 to 4 carbon atoms.Examples of the straight-chain or branched alkyl groups having 1 to 4carbon atoms include ethyl, methyl, straight-chain or branched propyl,and straight-chain or branched butyl groups.

The position of the hydroxyl group may vary. However, in the case of thecompound having two or more hydroxyl groups, they are preferablypositioned at adjacent carbon atoms. Preferably, the letter “a” is aninteger of 1 to 3, more preferably 2. Preferably, the letter “b” is aninteger of 0 to 3, more preferably 1 or 2. Examples of compoundsrepresented by formula (1) include p-tert-butylcatechol.

In (D) compounds represented by formula (2) above, examples of thehydrocarbon group having 1 to 30 carbon atoms represented by R² includethose that are the same as those exemplified with respect to thehydrocarbon groups having 1 to 30 carbon atoms represented by R¹, andpreferred examples are also the same as those for R¹. The position ofthe hydroxyl group may vary. However, in the case of the compound havingtwo or more hydroxyl groups, they are preferably positioned at adjacentcarbon atoms. Preferably, the letter “c” is an integer of 1 to 3, morepreferably 2. Preferably, the letter “d” is an integer of 0 to 3, morepreferably 0.1 or 2. Examples of compounds represented by formula (2)include 2,2-dihydroxynaphthalene and 2,3-dihydroxynaphthalene.

Examples of (E) polyoxyalkylene compounds include compounds representedby formulas (3) and (4) below.

R³O—(R⁴O)_(e)—R⁵  (3)

[In formula (3), R³ and R⁵ are each independently hydrogen or ahydrocarbon group having 1 to 30 carbon atoms, R⁴ is an alkylene grouphaving 2 to 4 carbon atoms, e is such an integer that the number-averagemolecular weight is from 100 to 3500.]

A—(R⁶O)_(f)—R⁷]_(g)  (4)

[In formula (4), A is a residue resulting from removal of all or some ofthe hydrogen atoms of the hydroxyl groups of a polyhydric alcohol having3 to 8 hydroxyl groups, R⁶ is an alkylene group having 2 to 4 carbonatoms, R⁷ is hydrogen or a hydrocarbon group having 1 to 30 carbonatoms, f is such an integer that the number-average molecular weight isfrom 100 to 3500, and g indicates the same number as the number of thehydrogen atoms having been removed from the hydroxyl groups for A.

In formula (3), at least either one of R³ or R⁵ is preferably hydrogen.Examples of the hydrocarbon group having 1 to 30 carbon atomsrepresented by R³ and R⁵ are the same as those exemplified with respectto the hydrocarbon groups having 1 to 30 carbon atoms represented by R¹,and preferred examples are also the same as those for R¹. Specificexamples of alkylene groups represented by R⁴ include ethylene,propylene (methylethylene), and butylene (ethylethylene) groups.Preferably, the letter “e” is such an integer to provide anumber-average molecular weight of 300 to 2000, more preferably 500 to1500.

Examples of the polyhydric alcohol having 3 to 8 carbon atomsconstituting the residue A are the same as those exemplified withrespect to the alcohol compounds of the present invention.

Examples of the alkylene groups having 2 to 4 carbon atoms representedby R⁶ are the same as those represented by R⁴ in formula (3). Examplesof the hydrocarbon group having 1 to 30 carbon atoms represented by R⁷include those that are the same as those exemplified with respect to thehydrocarbon groups having 1 to 30 carbon atoms represented by R¹, andpreferred examples are also the same as those for R¹. Preferably, atleast one of the R⁷ groups the number of which is represented by theletter “g” is preferably hydrogen atoms, and more preferably, all of theR⁷ groups are hydrogen atoms. Preferably, the letter “f” is such aninteger to provide a number-average molecular weight of 300 to 2000,more preferably 500 to 1500.

Esters for the above-mentioned (F) esters may be those whose alcohol maybe a monohydric alcohol or a polyhydric alcohol and whose carboxylicacid may be a monobasic acid or a polybasic acid.

Examples of the monohydric alcohol and polyhydric alcohol constitutingthe esters include those that are the same as the monohydric andpolyhydric alcohols exemplified with respect to the alcohol compounds ofthe present invention. Examples of the monobasic acid and polybasic acidinclude those that are the same as the monobasic and polybasic acidsexemplified with respect to the above-described esters for the base oil.

When the ester is produced using a polyhydric alcohol as the alcoholcomponent, the resulting ester may be a full ester in which all of thehydroxyl groups of the polyhydric alcohol are esterified, or a partialester in which some the hydroxyl groups remain unesterified. In the caseof using a polybasic acid as the carboxylic acid component, theresulting ester may be a full ester in which all of the carboxyl groupsare esterified, or a partial ester in which some of the carboxyl groupsremain unesterified.

No particular limitation is imposed on the total carbon number of theester. However, with the objective of improving processing efficiencyand tool life, the ester is an ester having a total carbon number ofpreferably 7 or more, more preferably 9 or more, most preferably 11 ormore. With the objective of preventing the generation of stain orcorrosion and improving compatibility with organic materials, the esteris an ester having a total carbon number of preferably of 60 or less,more preferably 45 or less, more preferably 26 or less, more preferably24 or less, most preferably 22 or less.

Polyhydric alcohols constituting (G) hydrocarbyl ethers of polyhydricalcohols may be those of usually dihydric to octahydric, preferablydihydric to hexahydric. Specific examples of polyhydric alcohols having3 to 8 hydroxyl groups are the same as those of the alcohol compounds ofthe present invention. These polyhydric alcohols may be used alone or incombination.

Preferred polyhydric alcohols include ethylene glycol, propylene glycol,neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane,pentaerythritol, sorbitan, and mixtures thereof. Among these polyhydricalcohols, most preferred is glycerin with the objective of improvingprocessing efficiency and tool life.

Examples of (G) hydrocarbyl ethers of polyhydric alcohols include thosewherein all or some of the hydroxyl groups of the above polyhydricalcohols are hydrocarbyl-etherified. Preferred are those wherein some ofthe hydroxyl groups of a polyhydric alcohol is hydrocarbyl-etherified(partial etherified product) with the objective of improving processingefficiency and tool life. The hydrocarbyl used herein referstoahydrocarbon group having 1 to 24 carbon atoms, such as an alkyl grouphaving 1 to 24 carbon atoms, an alkenyl group having 2 to 24 carbonatoms, a cycloalkyl group having 5 to 7 carbon atoms, an alkylcycloalkylgroup having 6 to 11 carbon atoms, an aryl group having 6 to 10 carbonatoms, an alkylaryl group having 7 to 18 carbon atoms, and an arylalkylgroup having 7 to 18 carbon atoms.

Among these hydrocarbyl groups, preferred are straight-chain or branchedalkyl groups having 2 to 18 carbon atoms and straight-chain or branchedalkenyl groups having 2 to 18 carbon atoms, and more preferred arestraight-chain or branched alkyl group having 3 to 12 carbon atoms andoleyl group (residue resulting from removal of the hydroxyl groups fromoleyl alcohol).

Preferably, (H) amines are monoamines. The carbon number of themonoamines is preferably from 6 to 24, more preferably from 12 to 24.The carbon number used herein refers to the total number of carbonscontained in a monoamine, and refers to the total carbon number when amonoamine has two or more hydrocarbon groups.

The monoamines that can be used in the present invention are primarymonoamines, secondary monoamines, or tertiary monoamines. Preferred areprimary monoamines with the objective of improving processing efficiencyand tool life.

Hydrocarbon groups bonding to nitrogen atoms of the monoamines may bealkyl, alkenyl, cycloalkyl, alkylcycloalkyl, aryl, alkylaryl, andarylalkyl groups. Preferred are alkyl and alkenyl groups with theobjective of improving processing efficiency and tool life. Alkyl andalkenyl groups may be straight-chain or branched but are preferablystraight-chain with the objective of improving processing efficiency andtool life.

Preferred monoamine used in the present invention include hexylamine(including all isomers), heptylamine (including all isomers), octylamine(including all isomers), nonylamine (including all isomers), decylamine(including all isomers), undecylamine (including all isomers),dodecylamine (including all isomers), tridecylamine (including allisomers), tetradecylamine (including all isomers), pentadecylamine(including all isomers), hexadecylamine (including all isomers),heptadecylamine (including all isomers), octadecylamine (including allisomers), nonadecylamine (including all isomers), eicosylamine(including all isomers), heneicosylamine (including all isomers),docosylamine (including all isomers), tricosylamine (including allisomers), tetracosylamine (including all isomers), octadecenylamine(including all isomers) (including oleylamine and the like), andmixtures of two or more thereof. Preferred are primary monoamines having12 to 24 carbon atoms, more preferred are primary monoamines having 14to 20 carbon atoms, and more preferred are primary monoamines having 16to 18 carbon atoms.

Any one or more of the above-described oiliness improvers (A) to (H) maybe used in the present invention. Among these oiliness improvers, onetype or a mixture of two or more types selected from (A) carboxylicacids and (H) amines are preferably used with the objective of improvingprocessing efficiency and tool life.

No particular limitation is imposed on the content of theabove-described oiliness improvers. However, with the objective ofimproving processing efficiency and tool life, the content is preferably0.01 percent by mass or more, more preferably 0.05 percent by mass ormore, more preferably 0.1 percent by mass or more on the basis of thetotal mass of the oil composition. In view of safety, the content ispreferably 15 percent by mass or less, more preferably 10 percent bymass or less, more preferably 5 percent by mass or less on the basis ofthe total mass of the oil composition.

Preferably, the oil composition of the present invention furthercontains an extreme pressure additive. Preferred extreme pressureadditives are sulfur compounds and phosphorus compounds.

No particular limitation is imposed on the sulfur compounds as long asthe properties of the oil composition are not impaired. However,preferred for use are dihydrocarbylpolysulfide, sulfidizing esters,sulfidizing mineral oils, zinc dithiophosphate compounds, zincdithiocarbaminate compounds, molybdenum dithiophosphate compounds andmolybdenum dithiocarbaminate compounds.

Dihydrocarbylpolysulfides are sulfur compounds generally referred to aspolysulfides or olefin sulfides, and specifically are represented by thefollowing formula (5):

R⁸—S_(h)—R⁹  (5)

wherein R⁸ and R⁹ may be the same or different and are eachindependently a straight-chain or branched alkyl group having 3 to 20carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylarylgroup having 7 to 20 carbon atoms or an arylalkyl group having 7 to 20carbon atoms, and h is an integer of 2 to 6, preferably 2 to 5.

R⁸ and R⁹ in formula (5) are preferably branched alkyl groups having 3to 18 carbon atoms derived from ethylene or propylene, particularlypreferably branched alkyl groups having 6 to 15 carbon atoms derivedfrom ethylene or propylene.

Specific examples of the sulfidizing esters include those produced bysulfidizing vegetable fats such as beef tallow, lard, fish oil, rapeseedoil and soybean oil; unsaturated fatty acid esters produced by reactingunsaturated fatty acids (including oleic acid, linoleic acid and fattyacids extracted from the aforementioned animal and vegetable fats) andvarious alcohols; and mixtures thereof, by any desired methods.

The sulfidizing mineral oil refers to a mineral oil in which elementalsulfur is dissolved. No particular limitation is imposed on the mineraloil for use in the sulfide mineral oil. However, specific examplesinclude paraffinic mineral oils and naphthenic mineral oils produced byrefining lubricating oil fractions that are produced by atmosphericdistillation and vacuum distillation of crude oil, by one of or anappropriate combination of two or more of refining treatments such assolvent deasphalting, solvent extraction, hydrocracking, solventdewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, claytreatment or the like. The elemental sulfur may be in a massive, powderyor molten liquid form but is preferably in a powdery or molten liquidform because it can be efficiently dissolved in the base oil. It isadvantageous to mix the elemental sulfur in a molten liquid state andthe base oil, both of which are liquid because the dissolution operationcan be completed in an extremely short period of time. However, becausethe elemental sulfur must be handled at a temperature equal to or higherthan its melting point, an extra heating apparatus is required thereforand a risk is accompanied due to the high temperature atmospherehandling. The molten liquid elemental sulfur is not always handledeasily. Whereas, the elemental sulfur in powder form is preferably usedbecause it is inexpensive and easy to handle and can be dissolved in asufficiently short period of time. No particular limitation is imposedon the sulfur content in the sulfide mineral oil. However, the contentis preferably from 0.05 to 1.0 percent by mass, more preferably from 0.1to 0.5 percent by mass on the basis of the total mass of the sulfidemineral oil.

The above-mentioned zinc dithiophosphate compounds, zincdithiocarbaminate compounds, molybdenum dithiophosphate compounds andmolybdenum dithiocarbaminate compounds are compounds represented by thefollowing formulas (6)- to (9), respectively:

In formulas (6) to (9), R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸,R¹⁹, R²⁰, R²¹, R²², R²³, R²⁴ and R²⁵ may be the same or different fromeach other and each independently a hydrocarbon group having one or morecarbon atom, and X¹ and X² are each independently oxygen or sulfur andmay be the same or different from each other.

In the present invention, among the above-mentioned sulfur compounds, atleast one type selected from the group consisting of dihydrocarbylpolysulfides and sulfidizing esters is preferably used because theeffects of improving processing efficiency and tool life can be achievedat further higher levels.

No particular limitation is imposed on the content of theabove-described sulfur compound. With the objective of improvingprocessing efficiency and tool life, the content is preferably 0.01percent by mass or more, more preferably 0.05 percent by mass or more,more preferably 0.1 percent by mass or more on the total mass of the oilcomposition. With the objective of preventing abnormal wear, the contentis preferably 50 percent by mass or less, more preferably 40 percent bymass or less, more preferably 30 percent by mass or less, particularlypreferably 20 percent by mass or less.

Examples of the phosphorus compounds used as an extreme pressureadditive include phosphoric acid esters, acidic phosphoric acid esters,acidic phosphoric acid ester amine salts, chlorinated phosphoric acidesters, phosphorous acid esters, and phosphorothionates. Thesephosphorus compounds may also be esters of phosphoric acid, phosphorousacid or thiophosphoric acid with alkanols or polyether alcohols, orderivatives thereof.

Among the above-described phosphorus compounds, preferred are phosphoricacid esters, acidic phosphoric acid esters, and acidic phosphoric acidester amine salts.

As described below, the oil composition for aluminum processing of thepresent invention can also be suitably used as an oil, for lubricatingother parts of a metal processing machine. When the oil composition ofthe present invention is used for sliding surfaces, acidic phosphorusacid esters and amine salts thereof are preferably used. Alternatively,the oil composition is used as a hydraulic oil, phosphorus acid estersare preferably used. Furthermore, the oil composition of the presentinvention is used both as an oil for sliding surfaces and as a hydraulicoil, at least one type selected from acidic phosphorus acid esters andamine salts thereof is preferably used in combination with a phosphorusacid ester.

The oil composition for aluminum processing of the present invention maycontain either one or both of sulfur compounds and/or phosphoruscompounds as an extreme pressure additive. However, with the objectiveof improving processing efficiency and tool life, the oil compositioncontains preferably phosphorus compounds or both sulfur compounds andphosphorus compounds, more preferably both sulfur compounds andphosphorus compounds.

No particular limitation is imposed on the content of theabove-described extreme pressure additive. With the objective ofimproving processing efficiency and tool life, the content is preferably0.005 percent by mass or more, more preferably 0.01 percent by mass ormore, more preferably 0.05 percent by mass or more on the basis of thetotal mass of the composition. With the objective of preventing abnormalwear, the content of the phosphorus compound is preferably 15 percent bymass or less, 10 percent by mass or less, 5 percent by mass or less onthe basis of the total mass of the composition.

In the present invention, either one of the above-described oilinessimprover or extreme pressure additive may be used. However, the oilinessimprover and extreme pressure additive are preferably used incombination because the effects of improving processing efficiency andtool life can be achieved at further higher levels.

Preferably, the oil composition for aluminum processing further containsan antioxidant. Examples of the antioxidant that can be used includephenolic antioxidants, amine antioxidants, zinc dithiophosphate-basedantioxidants, and antioxidants used as food additives.

No particular limitation is imposed on the phenolic antioxidants sincethey may be any phenolic compounds that have been used as antioxidantsfor lubricating oils. Preferable examples include alkylphenol compounds.

No particular limitation is imposed on the amine antioxidants since theymay be any amine compounds that have been used as antioxidants forlubricating oils. Examples of the amine antioxidant includephenyl-α-naphthylamines, N-p-alkylphenyl-α-naphthylamines, andp,p′-dialkyldiphenylamines. Specific examples of the amine antioxidantsinclude 4-butyl-4′-octyldiphenylamine, phenyl-α-naphthylamine,octylphenyl-α-naphthylamine, dodecylphenyl-α-naphthylamine, and mixturesthereof.

Specific examples of the zinc dithiophosphate-based antioxidants includezinc dithiophosphates represented by the following formula (18).

In formula (18), R⁵¹, R⁵², R⁵³ and R⁵⁴ may be the same or different fromeach other and are each independently a hydrocarbon group.

Antioxidants that have been used as food additives may also be used.Although such antioxidants partially overlap with the above-mentionedphenolic antioxidants, examples of such antioxidants include2,6-di-tert-butyl-p-cresol (DBPC),4,4′-methylenebis(2,6-di-tert-butylphenol),4,4′-bis(2,6-di-tert-butylphenol), 4,4′-thiobis(6-tert-butyl-o-cresol),ascorbic acid (vitamin C), ascorbic acid fatty acid esters, tocopherol(vitamin E), 3,5-di-tert-butyl-4-hydroxyanisole,2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole,1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline (ethoxyquin),2-(1,1-dimethyl)-1,4-benzenediol (TBHQ) and2,4,5-trihydroxybutyrophenone (THBP).

Among these antioxidants, preferred are phenolic antioxidants, amineantioxidants, and the above-mentioned antioxidants that have been usedas food additives. When it is considered that biodegradability isimportant, preferred are the above-mentioned food additive antioxidantsamong which more preferred are ascorbic acid (vitamin C), ascorbic acidfatty acid esters, tocopherol (vitamin E), 2,6-di-tert-butyl-p-cresol(DBPC), 3,5-di-tert-butyl-4-hydroxyanisole,2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole,1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline (ethoxyquin),2-(1,1-dimethyl)-1,4-benzenediol (TBHQ) and2,4,5-trihydroxybutyrophenone (THBP), among which more preferred areascorbic acid (vitamin C), ascorbic acid fatty acid esters, tocopherol(vitamin E), 2,6-di-tert-butyl-p-cresol (DBPC) and3,5-di-tert-butyl-4-hydroxyanisole.

No particular limitation is imposed on the content of the antioxidant.However, with the objective of maintaining excellent heat/oxidationstability, the content is preferably 0.01 percent by mass or more, morepreferably 0.05 percent by mass or more, most preferably 0.1 percent bymass or more on the basis of the total mass of the oil composition.Since a further improvement in effects of addition of the antioxidant asbalanced with the content can not be expected, the content is preferably10 percent by mass or less, more preferably 5 percent by mass or less,most preferably 3 percent by mass or less.

The oil composition of the present invention may further contain variousconventional additives in addition to those exemplified above. Examplesof such additives include extreme pressure additives (includingchlorine-based extreme pressure agents) other than the aforesaidphosphorus compounds and sulfur compounds; moistening agents such asdiethyleneglycol monoalkylethers; film-forming agents such as acrylicpolymers, paraffin wax, microwax, slack wax and polyolefin wax; waterdisplacement agents such as fatty acid amine salts; solid lubricantssuch as graphite, fluorinated graphite, molybdenum disulfide, boronnitride and polyethylene powder; corrosion inhibitors such as amines,alkanolamines, amides, carboxylic acids, carboxylic acid salts, sulfonicacid salts, phosphoric acid, phosphoric acid salts and polyhydricalcohol partial esters; metal deactivators such as benzotriazoles andthiadiazoles; antifoaming agents such as methylsilicone, fluorosiliconeand polyacrylates; and ashless dispersants such as alkenylsuccinicimides, benzylamines and polyalkenylamineaminoamides. No particularlimitation is imposed on the contents of these known additives when usedin combination. However, the additives are generally added in amounts sothat the total content of thereof is from 0.1 to 10 percent by mass onthe basis of the total mass of the oil composition.

No particular limitation is imposed on the kinematic viscosity of thealuminum processing oil composition of the present invention. With theobjective of making it easier to supply the oil to processing spots, thekinematic viscosity at 40° C. is preferably 200 mm²/s or lower, morepreferably 100 mm²/s or lower, more preferably 75 mm²/s or lower, mostpreferably 50 mm²/s or lower. With the objective of improving processingefficiency and tool life, the kinematic viscosity at 40° C. ispreferably 1 mm²/s or greater, more preferably 3 mm²/s or greater, morepreferably 5 mm²/s or greater.

EXAMPLES

Hereinafter, the present invention will be described in more detail byway of the following examples and comparative examples set forth inTable 1, which should not be construed as limiting the scope of theinvention.

Examples 1 to 9, Comparative Examples 1 to 6

Sample oils 1 to 14 that are oil compositions for aluminum processingwere prepared using the following Base Oils a to c, Alcohols A to C, andAdditives A to E.

(1) Base Oils

-   -   Base Oil a: mineral oil (kinematic viscosity at 40° C.: 32        mm²/s)    -   Base Oil b: trioleate of trimethylolpropane    -   Base Oil c: poly-α-olefin (kinematic viscosity at 40° C.: 30        mm²/s)

(2) Alcohol

-   -   Alcohol A: branched tridecanol    -   Alcohol B: 1,8-octanediol    -   Alcohol C: neopentyl glycol monooleate

(3) Additive

-   -   Additive A: tricresyl phosphate    -   Additive B: sulfidizing esters    -   Additive C: glycerin monooleate    -   Additive D: butyl stearate    -   Additive E: oleic acid

(4) Sample Oil

-   -   Sample Oil 1: Base Oil a (75 mass %), Alcohol A (25 mass %)    -   Sample Oil 2: Base Oil b (75 mass %), Alcohol A (25 mass %)    -   Sample Oil 3: Base Oil a (73 mass %), Alcohol A (25 mass %),        Additive A (1 mass %), Additive B (1 mass %)    -   Sample Oil 4: Base Oil a (75 mass %), Alcohol B (25 mass %)    -   Sample Oil 5: Base Oil a (75 mass %), Alcohol C (25 mass %)    -   Sample Oil 6: Base Oil b (20 mass %), Alcohol A (80 mass %)    -   Sample Oil 7: Base Oil b (2 mass %), Alcohol A (98 mass %)    -   Sample Oil 8: Base Oil c (75 mass %), Alcohol A (25 mass %)    -   Sample Oil 9: Base Oil a (84 mass %), Alcohol A (16 mass %)    -   Sample Oil 10: Base Oil a (90 mass %), Alcohol A (10 mass %)    -   Sample Oil 11: Base Oil a (75 mass %), Additive C (25 mass %)    -   Sample Oil 12: Base Oil a (73 mass %), Additive D (25 mass %),        Additive A (1 mass %), Additive B (1 mass %)    -   Sample Oil 13: Base Oil a (2 mass %), Additive D (98 mass %)    -   Sample Oil 14: Base Oil a (75 mass %), Additive E (25 mass %)

The following evaluation tests were carried out using oil compositionsfor aluminum processing of Examples 1 to 9 and Comparative Examples 1 to5.

(Tapping Test)

Processability of each of the aluminum processing oil compositions ofExamples 1 to 9 and Comparative Examples 1 to 5 was evaluated using acomparative standard oil that was diisodecyl adipate. More specifically,a tapping test was carried out under the following condition's usingeach of Examples 1 to 9 or each of Comparative Examples 1 to 5alternately with diisodecyl adipate. In Comparative Example 6, the sametapping test was carried out only by blowing compressed air withoutusing any oil.

-   -   Workpiece: AC8A    -   Tool Diameter: 8 mm    -   Tap Pitch: 1.25 mm    -   Tap Cutting Angle: 1.5 degree    -   Tap Chamfer Angle: 10 degrees    -   Bored Hole Diameter: 7.4 mm    -   Revolution: 360 rpm    -   Standard Oil: DIDA (diisodecyl adipate)    -   Supply Method: injected to a processing spot with MQ4        manufactured by TACO Co., Ltd.    -   Oil Supply Amount: 15 ml/h    -   Injected Air Pressure: 0.45 MPa

Tapping energy in the above test was measured, and tapping energyefficiency (%) was calculated using the following formula.

Tapping energy efficiency (%)=(Tapping energy derived when the standardoil was used)/(Tapping energy derived when each of the oil compositions)

The results are set forth in Table 1. Higher tapping energy efficiencyin the table means higher lubricity.

(Antiwear Evaluation Test)

In order to evaluate the antiwear properties for tools, the tappingenergy efficiencies of each of the aluminum processing oil compositionsof Examples 1 to 9 and Comparative Examples 1 to 5 against the standardoil were measured twice, i.e., after 10 holes were tapped and after 150hole were tapped, under the following conditions so as to calculate areduction rate of the energy efficiency after 10 holes were tappedagainst that after 150 holes were tapped.

It was deemed that the degree of reduction in tapping energy efficiencydue to the increased number of tapping was caused by tool wear. The testwas carried out, removing the aluminum adhering to the tool with a 10%sodium hydroxide solution every 10-hole tapping.

-   -   Workpiece: AC8A    -   Tool Diameter: 8 mm    -   Tap Pitch: 1.25 mm    -   Tap Cutting Angle: 1.5 degree    -   Tap Chamfer Angle: 10 degrees    -   Bored Hole Diameter: 7.4 mm    -   Revolution: 360 rpm    -   Number of holes: 10, 150 holes    -   Standard Oil: DIDA (diisodecyl adipate)    -   Supply Method: injected to a processing spot without using air        (DIDA), injected to a processing spot together with air with MQ4        manufactured by TACO Co., Ltd (sample oils).    -   Oil Supply Amount: 4.0 ml/min (DIDA), 15 ml/h (sample oils)    -   Injected Air Pressure: 0.4 MPa

(Evaluation Test of Discoloration)

Two sheets of aluminum plate A-1050 (60 mm×80 mm×1.2 mm) defined in JISH 4000 were prepared, on one of which 0.1 g of each oil composition waspoured dropwise and the other of which was placed thereon to sandwichthe oil. The sheets was applied with a load of 100 g from the top andwere allowed for stand at a temperature of 50° C. and a humidity of 95%for 100 hours. Thereafter, the surface on which the oil composition waspoured was observed to see whether the oil discolored or not.

The same evaluation was carried out using panels of cold-reduced carbonsteel sheet SPCC (60 mm×80 mm×1.2 mm) defined in JIS G 3141.

TABLE 1 Reduction Rate in Tapping Tapping Energy Energy EfficiencyEfficiency Discoloration (%) (%) A-1050 SPCC Example 1 Sample Oil 1  1245.0 NO NO Example 2 Sample Oil 2  119 4.6 NO NO Example 3 Sample Oil 3 124 5.2 NO NO Example 4 Sample Oil 4  122 5.2 NO NO Example 5 Sample Oil5  125 4.4 NO NO Example 6 Sample Oil 6  129 4.3 NO NO Example 7 SampleOil 7  131 4.3 NO NO Example 8 Sample Oil 8  127 4.5 NO NO Example 9Sample Oil 9  120 5.2 NO NO Comparative Sample Oil 10 103 7.2 NO NOExample 1 Comparative Sample Oil 11 111 8.2 NO NO Example 2 ComparativeSample Oil 12 118 6.7 NO NO Example 3 Comparative Sample Oil 13 105 5.0NO NO Example 4 Comparative Sample Oil 14 119 8.8 Yes Yes Example 5Comparative —  91 Tool broken — — Example 6 at 9th hole

It is apparent from the results in Table 1 that the aluminum processingoil compositions of the present invention are higher in tapping energyefficiency and thus excellent in lubricity and also low in tappingenergy reduction rate and thus excellent in antiwear properties. It isalso confirmed that the oil compositions of the present invention didnot discolor the aluminum panels.

APPLICABILITY IN THE INDUSTRY

The aluminum processing oil composition of the present invention can beused suitably for aluminum processing such as cutting, grinding,form-rolling, forging, pressing, drawing, or rolling. In particular, theoil composition is significantly useful as an oil for cutting, grinding,or form-rolling. The oil composition is supplied to spots to beprocessed by a minimal quantity lubrication system and particularlysuitable for use in minimal quantity lubrication cutting and grindingoperations.

Furthermore, the oil composition can be used as a lubricant for bearingportions, hydraulic devices, and gear portions so that these parts canbe lubricated with a single oil composition.

1. An oil composition for minimal quantity lubrication aluminumprocessing, comprising an alcohol compound having 1 to 8 hydroxyl groupsand 2 to 27 carbon atoms, in an amount of 16 to 100 percent by mass onthe basis of the total mass of the composition.
 2. The oil compositionfor minimal quantity lubrication aluminum processing according to claim1, wherein the alcohol compound is a straight-chain or branched alcoholhaving 3 to 18 carbon atoms or a cycloalkyl alcohol or alkylcylcoalkylalcohol having 5 to 10 carbon atoms.